Isomerization and separation of hydrocarbons are well developed and widely practiced in the petrochemical and petroleum refining industries. One constant concern for petrochemical and petroleum refiners is the utility consumption of isomerization processing units and separation units, for example, deisohexanizing processing units. One method of reducing utility consumption in isomerization processing is to use a heat exchange between hot streams with excess heat and cooler streams in need of energy. For instance, one known process flow in a typical isomerization process is to heat the feed stream by indirect heat exchange against the effluent of the isomerization zone.
While current methods are able to utilize heat energy from effluent isomerization streams to preheat a feedstock, the methods typically still require large amounts of utility consumption. For instance, some methods typically utilize additional heating of feedstock by passing the feedstock stream through a steam heater or a similar available source of high temperature heat. Due to the large scale of the processing, even a nominal improvement in energy efficiency can significantly reduce utility consumption.
Many isomerization and separation methods involve isomerization zones having multiple reactors. For example, in WO 2013/147787, an isomerization zone is disclosed which comprises three reactors. An effluent from each reactor is passed through a heat exchanger to heat the feed stream to the isomerization zone. U.S. Pat. Pub. No. 2013/0096356 discloses a similar method in which the isomerization zone includes two reactors.
While these methods may provide improved heat recovery from prior methods, it is desirable to provide methods and apparatuses for the isomerization and separation of hydrocarbon feeds that provide enhanced heat recovery. In addition, it is desirable to provide methods and apparatuses for the isomerization and separation of hydrocarbon feeds that exchange heat between the feed and a separation column. Other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.